Jesus, motherfucking Theresa
Tyler is Atheist and doesn’t mind being sacrilegious.
In this case, Tyler makes fun of three holy, or “saintlike” figures, Jesus, his mother Mary, and Mother Theresa. Tyler transposes Mother Theresa’s name into “motherfuckin' Theresa” to show he doesn’t fear any retribution from God for being disrespectful.
Another way you could interpret it is Tyler envisions a scenario where “Jesus’s mother” (Mary) is “fucking” “Mother Theresa”. So she couldn’t be the Virgin Mary anymore.
No matter how you choose to read it, it’s probably going to piss you off if you’re a devout Christian.
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